Tails + Fins

[Brommieslover]

Something is eating my fishes tails!
I have a 30l tank with
4 zebra danios
3 neon tetras
1 male betta
1 paradise fish
My fish are slowly looseing there tails and i dont know which fish to blame, so am having promlems doing anything about it. I watch them all the time and apart from the danios chasing each other, none of them show any aggression at all, not even the betta. Its getting to a point where i dont really want to look in the tank.
I dont think its fin rot theres no cotton or whitespot and the deco is "fish safe".
Iv been told the waters fine and i feed them once a day (could they be hungry?) sorry if thats a daft question.
If anyone could help me identify "the culprit" i would be very happy.
Thankyou

 

[black angel]

is there a fish that doesnt have any damage to its fins? some fish attack at night. my betta used to kill fish at night.

 

[Brommieslover]

The neons seem to be ok but they might just be to fast to be had? I guess it could be the betta but he seems to be really placid, whenever I watch him anyway!? Is there anything I could do to stop it happening? I dont really have anywhere i could separate them? Or is that the only answer?

 

[Flashfire]

Are the fish's fins red on the edges? If so you could very well have fin rot. Get a medication from your local pet store.

 

[Brommieslover]

There not red on the edges?

 

[SMSBrunetteGirl]

Remove your betta from the fish and see what happens.